Breakfasting on a slice of bread baked with ground-up seaweed could help burn more calories than half an hour on a treadmill, according to new research.

Trials on nearly 80 healthy but overweight men showed those fed scrambled egg on seaweed enriched toast felt so full they consumed 179 calories less a day.

The tests at Sheffield Hallam University are the first to involve adding the entire seaweed plant to the bread mix rather than breaking it down to extract various chemicals.

The bread - served with the crusts cut off - did not include any salt at all with the seaweed acting as a total replacement.

None of the men could tell the difference between an ordinary loaf and the slices seasoned with seaweed - which has a similar taste but far lower sodium levels.

As well as cutting salt intake, the seaweed also acted a bulking agent so the men felt fuller and less hungry.

So when they were presented with as many 400 gram bowls of pasta and tomato based sauce as they could eat for lunch some drew the line after a couple of bowls.

The seaweed was sourced from the pristine waters of the Scottish Outer Hebrides where it is harvested, dried and milled at a local factory.

Dr Craig Rose from The Seaweed Foundation which supported the study, said: "It is not as salty as normal bread but you don't notice any marine flavours and it is very acceptable.

"It is just like eating normal bread. It rises just the same and looks just the same. If it is white bread you might notice touch of green.

"But it would just look like basil or poppy seed which appeals to the bread companies anyway.

"It's not a salty taste it is mineral because seaweed is very rich in all the minerals. It has far more minerals than any land plant. It tastes minerally and works flavour wise."

The test panel split into groups of five was fed a 100 gram slice of normal bread one week and the enriched bread the next.

The scrambled egg was just to make the toast more palatable without butter. Researchers from Sheffield's Centre for Food Innovation checked how much they ate and blood pressure levels.

They found the men fed the seaweed bread consumed 179 less calories in a day, with 100 calories being significant for weight less.

Dr Rose added: "This is the first time that this has looked at the using the whole seaweed as a food. All that has happened is it has been dried and milled.

"Other works have looked at extracting chemical s from the seaweed and using them. So this study is very important in using whole seaweed to provide all the benefits. There is also on-going research showing it increases the shelf life of product.

"The seaweed acts a bulking agent in the stomach giving a feeling of fullness. It has sodium in low levels but far less than salt.

"It is also natural, sustainable, organic and adds nutrition. So unlike most bulking agents it is not just filling something out for the sake of cheapness."

Lecturer in nutrition Anna Hall, who led the study, said: "I tried the bread and really like it. It does look a bit different to normal wholemeal.

"The seaweed is fine granules so the bread looks a bit speckled but it tastes very nice."

Health food enthusiasts are familiar with seaweed broken down into elements such as kelp.

"But we wanted to use the whole seaweed because it is rich in fibre as well as minerals and what we have achieved is a very welcome addition to the research around seaweed and health."

Previous research has looked at using seaweed as a salt substitute with pasta. As well as using it in bread the university is also investigating applying the principle to a range of meat products including sausages, she added.